The major aim of this study is to examine the impacts of physicians' interactional styles and patients' perceptions of their disease experiences on patients' understandings of their treatment plans and compliance with those plans among chronically ill, middle aged and elderly persons. Compliance is viewed in this context as one form of illness behavior in contrast to self-care or self-treatment. The secondary aim is to compare these relationships between women and men. This research is based on a conceptual model that combines the perception of the chronic disease experience, factors in the health belief model that have been found to be consistent predictors of illness behaviors and aspects of the physician-patient relationship. An initial random sample of 2000 non-institutionalized persons aged 45 and older will be drawn from the active membership of a large health maintenance organization (HMO) in a midwestern, industrial SMSA and screened to select those with arthritis, diabetes or hypertension, to yield a final sample of approximately 800. Such a sample is appropriate for this study because neither access to nor quality of health care varies by race or gender in the HMO, a situation not found in the general population. Although generalizability of results will be somewhat limited by the nature of the sample, the potentially confounding effects of differential access to health care are eliminated while access to medical records is assured. Data will be collected from three sources. Face-to-face interviews with sample members will provide data on patients' perceptions of physicians' interactional styles, the chronic disease experience, understanding of and compliance with treatment plans and self-care behaviors. Clinical information on these treatment plans and clinical outcomes will be obtained from medical record reviews. In addition, the respondents' primary care physicians will be surveyed with self-administered questionnaires, to assess their own perceptions of their interactional styles. The joint examination of compliance and self-care and the addition of physician-patient interactions and the chronic disease experience to the health belief model are unique features of this study.